HP Shop Manager Horizontal logo prepared for dark backgrounds.

Parts

Know what is on the shelf, and what it cost

On-hand and average cost are worked out from every part that has moved, not from a number somebody typed.

The catalog

Parts with real specs
A crankshaft is a stroke and two journal diameters. Search on the numbers and find the one you already have.
Five price levels
Retail, trade, and whatever you call the racer who is in every week.
Bins and margins
Where it is, what it cost, what it sells for, and the margin — while you are quoting.
Kits and templates
A gasket set or a standard teardown, added in one go.
Customer property
The crank on your rack that belongs to somebody else is tracked as theirs.

Keeping it straight

Every movement leaves a line
What came in, what went out, onto which ticket, and who did it. The shelf and the screen cannot drift apart quietly.
Minimums and reorder points
Set them once and the shortage list keeps itself, counting what is already on order.
Counts that hold still
Start a count and the expected numbers freeze, so a sale mid-count does not make it look wrong.
Bring in what you have
Import customers, parts and rates from a spreadsheet, with a dry run first.